Tertiary Consumers (trophic level 4)- carnivores that obtain their energy by consuming other carnivores. Energy obtained is in the most indirect method- from the bodies of secondary consumers. Example: foxes, owls, killer whales

3) Decomposers- these are organisms that feed on dead matter and break it down to release chemical energy back into the soil for plants to re-use them. Example: fungi, bacteria, worms

At each successive level, a great deal of energy is lost. The transfer of energy between organisms is very inefficient. As a result, only a small amount of energy is obtained when a secondary consumer eats a primary consumer. Therefore, the higher up the trophic level, the fewer the number of animals since they must eat larger amounts of animals of food in order to obtain enough energy. Because so much energy is lost as you move through the food chain, there are typically no more than 4 or 5 links in the food chain. Most of the energy exits the food web as heat from metabolic processes by the organism itself or by decomposers that use the organism's waste as food. This principal is known as the pyramid of numbers.

Food Web- this is a complex network of food chains in an ecosystem (group of animals and plants which interact with each other and their environment). Because there can be no more than 4 or 5 links in the food chain, animals eat a variety of food in order to meet their energy needs. These interconnected food chains form a food web.

A changes in one population in a food chain can affect the other populations in the food chain. For example, let's use the tree, giraffe, lion food chain. If there are too many giraffes, then there will not be enough trees for the giraffes to eat. Eventually, the giraffes will starve and die. Fewer giraffes will allow the trees to grow and multiply. However, fewer giraffes will result in lions starving to death. Fewer lions may lead to more giraffes.

b. Explain matter transfer (e.g. biogeochemical cycles) in ecosystems

There are several processes through which elements that sustain life are coninuously made available to living organisms.

Nitrogen Cycle- Organisms need nitrogen in order to make amino acids, which is in turn used to build protein. Except for bacteria, organisms cannot use nitrogen directly from the atmosphere. The bacteria, which lives on the roots of legumes, bind the nitrogen atoms to hydrogen atoms to form ammonia, NH3, in a process known as nitrogen fixation. Other bacteria in the soil converts ammonia into nitrates and nitrites during nitrification. Producers can take these substances in and use them to make proteins. Consumers consume the producers who in turn use these proteins to make new proteins. When organisms die, decomposers return the nitrogen back into the soil as ammonia. Bacteria may again change the ammonia into nitrates or nitrites or into nitrogen gas (denitrification, which is internal respiration by bacteria).

Hydrological Cycle- Water is constantly moving in a cycle through organisms and the environment.

The cycle typically begins with the process called evaporation, that is driven by the sun's energy. As the water molecules are heated, the water becomes gas particles and moves up into the atmosphere where it condenses around small particles, forming clouds. If the temperature stays warm, water droplets continue to form around particles, growing larger and larger.

These water particles are returned to earth, called precipitation, as rain, sleet, hail, or snow (sublimation). On land, the water molecules may be heated and evaporate; it may seep in the soil and become ground water; it may run across the surface as runoff, and empty into bodies of water (where it may become heated and evaporate).

The water that seeps into the ground (called percolation) may be taken in by the roots of plants (xylem) with is used by the plants, along with carbon, in photosynthesis where it breaks it down into new combinations that creates sugar and oxygen.

Animals that breathe the oxygen and eat the sugar recombine those materials to make water as one of the products of respirations. Animals release the water back into the environment. Water also returns to the atmosphere by plants in a process called transpiration when plants undergo cellular respiration which involves the breakdown of food molecules for energy into CO2 and water.

Water that percolates into the ground may seep far enough until it reaches a layer or impermeable rock. Caught between the impermeable rock and saturated soil above it, it may move inside the ground through underground "rivers". The top level of the ground water is called the water table. Depressions in the Earth that reveals the water table are called either lakes or rivers.

Carbon Cycle- Organic molecules that make up all living things contain carbon. Carbon is also found in air, oceans, and rocks. In the air, it's found as carbon dioxide. In the ocean, it's CO2 dissolved in water. Carbon cycles through the living and nonliving environment. Plants take in CO2 along with water to build organic molecules during photosynthesis. Carbon may turn into the air in several ways:

respiration- this is a process where organisms use oxygen to release energy from carbon-containing organic molecules. CO2 is a product of this processe and is released into the air.

Combustion- when material burns, carbon that Is tied up in the wood of trees for hundreds of years is released. Some carbon is also locked away for millions of years in the form of fossil fuel (coal, oil, and natural gas).

Erosion- many marine organisms contain carbon in their calcium carbonate shells. Wen they die, their shell forms sediments on the bottom of the ocean. Over millions of years, these sediments form limestone. The carbon may be tied up in the limestone for years. During erosion, the limestone may become exposed and undergo chemical changes that returns the carbon into the atmosphere.

Phosphorus Cycle- phosphorus enters the environment from rocks or deposits laid down many years ago. Weathering and erosion releases phosphorus as phosphate ions which are soluble in water. Phosphorus is incorporated into many molecules essential to life. When plant materials and waste products decay through bacterial action, phosphate is released and returned into the environment for reuse. Much phosphate is washed into the water due to erosion and leaching where water plants and algae utilize the phosphate as a nutrient. A large percentage of the phosphate in water is precipitated from the water as ion phosphate which is insoluble. If it's in shallow sediments, it may be readily recycled back into the water for further reuse. In deeper sediments in water, it's available for use as part of a general uplifted of rock formations for the cycle to repeat itself.

Human influences of the cycle comes from synthetic fertilizers. Unused phosphate not used by plants is washed away and eventually ends up in bodies of water where it may be redissolved and recycled as a problem nutrient.

c. Distinguish between abiotic and biotic factors in an ecosystem

Abiotic Factors- Organism in a biosphere are acted upon by abiotic (non-living) factors. Factors include things such as:

Temperature: affects metabolism, range is 0 to 50 degree C

Water: adaptations for water balance and conservation help determine a species' habitat range

Light: Solar energy drives nearly all of the ecosystem. Availability of light can determine habitat. In aquatic environments, where water reflects and absorbs certain wavelengths, most photosynthesis takes place near the surface of the water. Animal and plant behavior is sensitive to photoperiods (duration of an organisms' exposure to light).

Soil: physical structure, pH, and mineral composition of soil limit distribution of plants and hence animals that feed on them.

Wind: amplifies effects of temperature by increasing heat loss by evaporation and convection.

Biotic Factors-livings things that shape an ecosystem. The biotic components found in a location are affected by abiotic factors in that area. There is a finite amount of items that can be alloted for growth, reproduction, obtaining nutrients, etc.

Biotic factors include:

animals- mammals, birds, reptiles, insects, fish, amphibians

plants

fungi

bacteria

decomposers

herbivores

carnivores

producers

d. Compare the roles of photosynthesisand respiration in an ecosystem

Photosynthesis- this is a series of chemical reactions that involves the production of glucose from CO2 and water (transported through the xylem vessels) and energy from sunlight. Photosynthesis only takes place in some plants and deep sea bacteria. The chemical equation for photosynthesis is:6CO2 + 6H2O + solar energy => C6H12O6 + 6O2

Photosynthesis produces oxygen and carbohydrates (needed for internal respiration) while respiration produces CO2 and water (needed for photosynthesis).

At times, one of the two is occurring at a faster rate than the other, which means that excess amounts of its products are produced, and not enough of the substances it needs are being made in the plant.

Compensation Points- there are two points in a 24 hour period where the process of photosynthesis and respiration are exactly balanced.Dawn- compensation pointmidday- bright light, faster photosynthesisdusk- compensation pointmidnight, no light, respiration.

e. Describe interrelationships within and among ecosystems (e.g., predator/prey)

Predation- relationship in which one organism preys on another as a source of food. Example: owl (predator) hunting a field mouse (prey).

Competition- when two organisms have the same niche, they must compete for the available resources.

Symbiosis- close and permanent associations between organism. There are three different types of symbiosis relationships:

1. Parasitism- relationship in which one organism derives benefit at the expense of the other. Example: tapeworm (parasite) takes nourishments from the dog.

2. Commensalism- relationship in which one organism derives benefit while the other is neither harmed nor receives any benefits. Example: clown fish and sea anemone (clown fish is covered in a secretion that makes it immune to a sea anemone's attack. The clown fish can find protection with the anemone while bringing the anemone no benefit or harm).

3. Mutualism- relationship in which both organisms benefit from each other and no harm is done to either organisms. Example: ant and acacia tree (The ant protects the tree from herbivores from eating the tree as well as clearing vegetations away from the tree that may compete for resources. The tree provides a home for the ants).

f. Identify and explain factors that affect population types and size (e.g., competition for resources, niche, habitats, species and population interactions, abiotic factors)

Limiting Factors- limiting factors are things in the environment, biotic or abiotic, that prevents a population from growing any larger. For example, a habitat may have enough space and water to house 20 capybaras, however, if there is only enough food for 10 capybaras, then the population will not grow any larger. Food, in this example, is the limiting factor.

Carrying Capacity- this is the maximum population size of the species that the environment can support over a long period of time.

Natural disasters- affects population. For example on the Galapagos Island, drought may reduce the quantity of seeds on which finches eat, driving down the population.

Intraspecific competition- competition between members of the same species. Competition among members of one species for a finite resource (food, for ex) can cause a sharp drop in population.

Interspecific competition- all the ecological requirements of a species constitutes its ecological niche. The dominant requirement is food, but can also be nesting sites or a place to sun (plants). When two species share overlapping ecological niches, they may be forced into competition for the resources of that niche. Overtime, interspecific competition can result in evolutionary changes that reduce the intensity of competition (characteristic displacement).